Docking of an engine boat to a port or a fixing platform can sometimes be very difficult and it may turn into a nightmare for boat users, as there may not be a sufficiently large area for docking the boat at the port. This may result the boat user to make numerous maneuvers for docking the boat.
According a well-known docking method of twin-outboard-engine boats (or twin-inboard with outer drive boats), angles of the propellers of the engines are angled inward or outward (i.e. engines are rotated around the vertical axis in a way that their propeller thrust directions will intersect with each other) and then each propeller is provided thrust in different directions.
For instance, as it is explained in U.S. Pat. No. 6,561,860, when the boat is intended to move to the left direction, the engines so the propellers angled outward and the engine on the left is provided forward thrust, while the engine on the right is provided backward thrust. Therefore, the force components of the thrusts in the axial direction (i.e. along the longitudinal axis of the boat) balance each other, and the force components in the left direction (along the width of the boat) are added together, and thus the boat moves in the left direction.
In order for the engines to be angled to one another, an extendible rod to be connected from ends to the engines is used. While the boat is in its normal course, the engines are maintained parallel to each other (in other words, the propeller thrust directions extend collaterally), in which case the rod is prevented from getting longer or shorter; therefore, when one of the engines turns into a direction, the other engine turns into the same direction synchronously.
The rod is particularly needed to be extended or shortened when the boat is docking to the port/wharf. However, it requires a lot of effort for the user to properly move the boat in a transverse direction (sideward), since the fact that the engines have been angled is not enough for the boat to properly move in a transverse direction, and therefore to dock to the port/wharf properly. The extent to which the engines have been angled for the proper transverse movement of the boat (the degree at which the propeller thrust directions intersect with one another) changes depending on the external geometry of the particular boat and the location of the center of gravity of same.
As it is shown in FIG. 1, each boat (1) can move properly in the transverse direction only when it is pushed from a certain point in the transverse direction on the longitudinal axis (2). For instance, this optimal thrust point is an “A” point for some boats, “B” point for some, and “C” for some others. When the boat is not pushed from the said optimal point, it makes an improper movement in the transverse direction, which is undesired for the boat user, because the maneuver control of the boat becomes difficult.
U.S. Pat. No. 6,561,860 discloses a boat maneuver arrangement comprising an adjustable rod, two ends of which are connected to an engine. In the maneuver mode, the boat opens or closes in a way that it will be displaced to a maximum or minimum value, and the boat is provided to move in the transverse direction by rotating the propellers in opposite directions. However, the arrangement in U.S. Pat. No. 6,561,860 does not offer a solution for providing a proper transverse movement to the boats of different structural characteristics (of different external geometrical structure and having center of gravity at different points).
U.S. Pat. No. 7,467,595 discloses an arrangement for maneuver control in a twin-engine boat. Here, hydraulic pistons which can be extended or shortened and which are connected both in between the engines and to the other parts of the engines have been used. Each engine can be angled at an amount independent of the other engine. The amount of angling is determined by a control unit, based on the user commands. The user controls a “joystick” manually for the transverse movement of the boat, during which the amount of rotation that the joystick performs is made digitized by means of sensors and sent to the control unit. The control unit generates signals driving the hydraulic pistons and valves depending on the data that it has received. By means of the arrangement in U.S. Pat. No. 7,467,595, even if the proper transverse movement of the boats with different characteristics is possible in theoretical terms, it is not possible practically, because the user moves the boat in a transverse direction manually (with the help of joystick) each time. Also, the arrangement in U.S. Pat. No. 7,467,595 is quite complicated and high-cost because of the equipment used.